Thermostat.



G. l. LEONARD.

THERMOSTAT.

APPLICATION FILED DEC.28,1916.

Patented Sept. 10, 1918.

I raven/Z27 eo ye Zeonard UNITED STATES PATENT oE IoE.

GEORGE I. LEONARD, OF CHICAGO, ILLINOIS, ASSIGNOR TO LEONARD PUMP AND MOTOR 00., OF CHICAGO, ILLINOIS, A CORPORATION OF MAINE.

THERMOSTAT.

Specification of Letters Patent.

Patented Sept. 10, 1918.

A plication filed December 28, 1916. Serial No. 139,435.

To all whom it may concern:

Be it known that I, GEORGE I. LEONARD, a citizen of the. United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Imrovement in Thermostats, of which the fol owing is a specification.

My invention relates, more particularly, to thermostats for use as elements in refrigerating apparatus, to control by electrical means, the supplying-0f the refrigerating medium to the refrigerating coils, though, as will be understood from the following it is not limited to thermostats for this purpose.

My object is to provide a novel, simple and economical construction of thermostat which shall be positive in operation, respon- SlVG to relatively slight changes in temperature, whereby in the case of its use in refrigerating apparatus the temperature in the refrigerating chamber may be maintained substantially uniform; shall not be liable to impairment in use; and shall be so constructed that the elements thereof, actuated tingmaterial carried by a base 9, wires, such by the change in temperature, shall not be subjected to undue pressure in the operation of the device.

Referring to the accompanying drawing-- Figure 1 is a plan view of a thermostat constructed in accordance with my invention. Fig. 2 is a side View of the thermostat. Fig. 3 is a section taken at the line 3 on Fig. 1 and viewed in the direction of the arrow showing the movable electrical contact of the device in one position; and Fig. 4, a similar view showing the said contact in its other position.

The stationary contacts of the device are represented at 5 and 6, these contacts, which are spaced apart, being mounted on, and secured as by screws 7 to a block 8 of insulaas those shown at 10 and 11 being connected with the respective contacts 5 and 6 and serving the purpose as is usual in constructions of this character. The movablecontact-member of the device is represented at 12 and in the form shown is a U-shape vmember pivoted at its arms 13 and 14 on a pin 15 which is mounted at its opposite ends midway between the contacts 5 and 6 in a clip 16 secured to the base 9, and in a post 1:7 rising from this base. The arm portion 13 of the contact 12 extends at opposite Sides of the pivot 15 in the form of wings 18 and 19 extending at an angle to each other and having flanged lower edges as represented at 20, these wings being adapted, upon rocking the member 12, to alternately contact at their flanged portions 20, with the upper flanged ends of the contacts 5 and 6, respectively, the contact produced in the particular arrangement shown being an abutting contact. The other arm 14 of the movable contact contains a recess 21 in its upper edge into which the lower end of a spring 22, extends and yieldingly bears, the upper end of this springbeing connected with a pin 23 which is longitudinally adjustable in the post 17, to vary the tension .of the spring 22, this pin being held in adjusted position by a set-screw 24. The spring is so constructed and arranged as shown, that it acts against the movable contact in either of its two positions (Figs. 3 and 1) and thus holds either the wing 18 or 19 against the cooperating stationary contact 5 or 6, as the case may be, by this arrangement it being only necessary, in shifting the contact 12 from one to the other of the stationary contacts, to swing the contact 12 from one side of its pivot to a slight distance only beyond the pivot at its opposite side, the spring completing the swing and causing the contact to snap to contacting position. The arm 17 is held to the base 9 by screws 17 to one of which a wire 25 electrically connected with the movable'contact 12 through the pin 15, and post 16, is connected, this wire serving the purpose as is usual in constructions of th1s character.

The upper edges ofthe wings 18 and 19 converge downwardly toward the pin 15 as shown and adjacent the latter are cut away, as indicated at 26, to provide the shoulders 27 ..and 28 at opposite sides of the pin 15, adapted to be alternately engaged by mecha nism for rocking the contact 12 on its pivot 15 into and out of engagement with the contacts 5 and 6, and of which, in its preferred form, the following is a description: Rising from the base 9 is a post 29 preferably pivoted thereon, through the medium of a bolt 30, to be adjusted about a vertical axis for a purpose hereinafter explained. The post 29, which is preferably of rectangular shape in cross-section as shown, carries a pair of to opposite faces of the post 29 to extend laterally therefrom toward the contact mechanism, hereinbefore described, with their extremities spaced apart. The members 31 and 32 are so constructed that under vanations in temperature their free end portions will move, this movement being utilized by means hereinafter described, to actuate the movable contact device 13. A desirable construction of each of the members 31 and 32 which are of the same construction, involves the provision of a bar or strip 33 of hard rubber to a face of which a strip 34 of metal, such as steel, is firmly secured thereto at intervals, as by the rivets 35. The variation in the co-efficients of expansion and contraction of these two materials is so great that. under relatively slight changes in temperature the shape of the members 31 and 32 will change and as they are fixedly held at one end to the post 29, their free ends will be caused to move, these members 31 and 32 being preferably so arranged that the metal strips 34 are on opposite sides of the'bars 33 and thus when these members distort under changes in temperature their outer free ends will move toward, or ina direction away from, each other. The outer free ends of the members 31 and 32 are provided with plates 36 secured thereto by screws 37, the outer edges of the plates 36 being bifurcated, as indicated at 38. A link 39 of angle-shape is flexibly connected at the bifurcated portion 38 of the plate 36 on the member 31, through the medium of a pin 40 extending through the arms of this plate and said link, whereby this link, which carries a finger 41 rigid therewith for actuating the movable contact 13, as hereinafter described, may move independently of the member 31. The other' plate 36 isconnected by a pin 42 pass ng through the arms of the bifurcated portion 38 of this plate, with a link 43, the outer end of which extends through an elongated slot 44 in the link 39, and to which latter the link 43 is pivoted as throu h the medium of a pin 45 carried by the lin 39 and adapted to be inserted into any one of the openings.

46 in the link 43, the plurality of openings 46 permitting of the adjustable connection of the link 43 with the link 39;

From the foregoing it will be readil understood that the link mechanism invo ving the links 39 and 43 form a compound lever device connecting the members 31 and 32 and the finger 41, whereby a relatively slight movement of the extremities of the members 31 and 32 toward or away from each other will be translated into a relatively great movement of the finger 41, sufiicient to cause the movable contact 13 to be shifted from one to the other of the stationary contacts 5 and 6 under relatively slight changes in temperature, the finger 41 for this purpose being 9 tion 13 of the device 12 and in moving in one direction engages the shoulder 28 and swings the member 13 beyond central position whereuponthe spring 22 forces it into engagement with the contact 5, and in moving in the opposite direction engages the shoulder 27 swinging the contact beyond central position, whereupon the spring 22 snaps the contact into engagement with the stationary contact 6.

It will be noted from the foregoing that the movement of the finger 41, necessary to shift the movable contact from one of its positions to the other thereof, is relatively slight, inasmuch as the spring 22 completes the shifting movement, and, furthermore, that the movable contact 13 resists the movement of the finger 41 through a relatively slight movement only of the latter, and as soon as the spring starts to complete the turning movement of the contact 13, the pressure is removed from the finger 41 and it is free to continue its movement in the same direction without resistance, thus avoiding any danger of impairing the connections between operating parts, and-the producing of a set in the members 31 and 32, which might occur, in the hard rubber strips 33 if the finger 41 were restrained against free movement under the action of the members 31 and 32 in becoming dis torted.

, The adjustment of the device for causing the movable contact 13 to be shifted from one to the other of the stationary contacts to cause the device to operate responsively to cooler or Warm temperature as desired, is

effected through the medium of the pivotof'set-screws 47 having screw-threaded engagement with bosses 48 rising from the base 9 and adapted to bear against the opposite sides of a lug 49 extending laterally from the post 29. Assuming that it is desired the movable contact 13 be shifted to electrically engage the contact 5 when the temperature to which the device is'subjected is eater than that at which the device would e operated when set as shown in the drawing, the operator would adjust the screws 47 in the bosses 48 to swing the post 29 in a counter-clockwise direction, in Fig. 1, thus initially positioning the finger 41 farther from the axis of the movable contact 13. If, however, it is desired that the contact member be operated at a lower temperature than that at which it would be operated when in the position shown in Fig. 1, the screws 47 would e ad usted to swing the post 29 in a clockwise direction (Fig. 1) which would initially position the finger 41 closerto the axis of 131 the member 13, it being possible by the adjustment thus provided to adjust the device to operate at different temperatures as desired, With practical accuracy.

The adjustment of the device for causing the movable contact to be shifted from one of the stationary contacts to the other thereof under varying ranges of temperature as desired is effected by adjusting the tension of the spring 22 as by adjusting the pin 23 lengthwise inthe post 17. The greater the pressure exerted by the spring 22 the less sensitive is the instrument to changes in temperature, as a greater pressure must be exerted by the finger against the contact to throw it from one position to the other.

By the arrangement provided the instru ment is rendered operative to shift the movable contact from one stationary contact to the other thereof under as slight a variation in temperature as two degrees.

While I have illustrated and, described a particular construction in Which my invention is embodied, I do not Wish to be understood as intending to limit it thereto, as the same may be variously modified and altered Without departing from the spirit of my invention, it being my intention to claim my invention as fully and completely as the prior state of the art will permit.

What I claim as new and desire to secure by Letters Patent is 1. In a thermostat, the combination of a pair of members supported, and constructed, to move relative to each other under variations in temperature to which they are subjected, a third member pivoted to one of said "first-named members, and a fourth member pivoted to the other of said first-named members and pivoted at its outer end to said third member intermediate the outer end of the latter and its pivotal connection with one of saidrfirst-named members.

2. In a thermostat, the combination of a pair of members supported, and constructed, to be bodily movable for the purpose of adjustment and movable relative to each other under variations in temperature to which they are subjected, a third member pivoted to one of said first-named members, and a fourth member pivoted to the other of said first-named members and pivoted at its outer end to said third member intermediate the outer end of the latter and its pivotal connection with one of the said first-named members.

3. Ina thermostat, the combination of a pair of members mounted on a pivotal support to permit adjusting said members bodily, said members being supported, and constructed, to move relative to each other un der variations in temperature to which they are subjected, a third member pivoted to one of said first-named members, and a fourth member pivoted to the other of said first-named members and pivoted at its outer end to said third member intermediate the outer end of the latter and its pivotal con- Eection with one of said first-named memers.

4. In a thermostat, the combination of a pivotallysupported member, a pair of members secured to said first-named member at oppositesides thereof and extending generally in parallel relation to each other and constructed to move at their free ends rela tive to each other under variations in temperature to which they are subjected, a third member adapted to be operated by sald pair of members, and means for actuating said third member from said pair of members operating to translate relatively slight movement of said pair of members into the relatively great movement of said third member.

GEORGE I. LEONARD. 

